The present invention relates to an electronic control apparatus, which includes both electrical and mechanical components. More specifically, the present invention relates to a control apparatus that includes a pressure medium control function, in addition to electronic control functions.
This type of control apparatus typically comprises a printed circuit board enclosed within a housing. The housing material can be either metal (usually aluminum) or plastic. The printed circuit board can be either one-sided or two-sided; i.e., with electronic components on one or both sides. These components may be wired using pass-through technology, or may be surface mounted (SMD) components that are soldered directly to the printed circuit board.
The type of electronic control apparatus which also includes a mechanical function is known as xe2x80x9cmechatronic.xe2x80x9d This apparatus type processes both electrical and mechanical input parameters. A typical mechanical input parameter would be in the form of a pressure medium, such as compressed air.
As disclosed in German patent document DE 29 602 711 U1, which is incorporated herein by reference, a printed circuit board can include one or several pressure sensors, in addition to various electronic components.
This known type of pressure sensor is configured as an SMD component in the form of an IC. A typical configuration would consist of a block-shaped plastic housing with leads, within which a semiconductor pressure sensor is included. The pressure sensor housing would also include a bore-shaped opening, for the intake of the pressure medium. As such, the pressure sensor housing, and its associated electronic components, are subjected to the same pressure medium as is directed to the pressure sensor. Therefore, those applications requiring higher levels of a pressure medium to be measured would necessitate the use of higher strength housing walls, in addition to a pressure-sealed housing cover. Moreover, the electronic components within the housing would also have to be designed to withstand the higher pressures.
Accordingly, it is an object of the present invention to disclose a mechatronic type of control apparatus, where an IC pressure sensor is installed on a printed circuit board, without requiring the overall housing, as well as the electronic components mounted on the printed circuit board, to be subjected to the pressure medium level applied to the pressure sensor.
This object is attained by means of an electronic control apparatus having both electrical and mechanical functions, including the pressure measurement of a pressure medium. The inventive control apparatus is comprised of a housing and a cover, with one or more printed circuit boards attached to the interior side of the cover. Electronic and mechanical components can be mounted on one or both sides of the printed circuit board(s), including at least one pressure sensor mounted on the interior side of a printed circuit board. A pressure conduit, mounted within the housing, receives a pressure medium to be measured at one open end, and channels this pressure medium to the pressure sensor through its other open end. This other open end of the pressure conduit encloses the pressure sensor within a pressure tight seal against the printed circuit board, so that the other components on the printed circuit board, as well as the overall housing, are isolated from the pressure medium to be measured.
In one preferred embodiment of the present invention, a pressure equalization chamber, having the same cross-sectional surface area as the aforementioned other open end of the pressure conduit, is attached to the printed circuit board, directly opposite the other open end of the pressure conduit on the other side of the printed circuit board. A bore through the printed circuit board enables the pressure medium to enter the pressure equalization chamber, thus equalizing the pressure on both sides of the printed circuit board, to avoid stressing the board when the pressure medium is applied.
Another preferred embodiment utilizes a heat sink type of printed circuit board mounted directly to the interior surface of the cover, thus providing rigidity to the heat sink board for withstanding the applied pressure medium.